Accelerated age-related decline in processing resources in schizophrenia: evidence from pupillary responses recorded during the span of apprehension task

Blunted pupil light reflex is associated with negative symptoms and working memory in individuals with schizophrenia

Two largely separate lines of research have documented altered pupillary dynamics in individuals diagnosed with schizophrenia. An older set of studies has demonstrated reductions in the pupillary light reflex (PLR) in individuals with schizophrenia; however, clinical and cognitive correlates of this blunted PLR have been relatively unexplored. More recently, a large body of work has demonstrated reductions in pupillary dilation in response to cognitive demands in individuals with schizophrenia, and the degree of this blunted pupil dilation has been related to more severe cognitive deficits and motivational negative symptoms. These clinically relevant alterations in the cognitive modulation of pupil size have been interpreted as reflecting insufficient information processing resources or inappropriate effort allocation. To begin to bridge these two lines of work, we investigated the PLR in 34 individuals with schizophrenia and 30 healthy controls and related the amplitude of the PLR to motivational negative symptoms and cognitive performance. Consistent with prior work, we found that the PLR was reduced in individuals with schizophrenia, and furthermore, that these measurements were highly reliable across individuals. Blunted constriction was associated with more severe motivational negative symptoms and poorer working memory among individuals with schizophrenia. These observed correlates provide a bridge between older literature documenting an altered PLR and more recent work reporting associations between negative symptoms, cognition, and blunted pupillary dilation in response to cognitive demands in individuals with schizophrenia. We provide possible mechanistic interpretations of our data and consider a parsimonious explanation for reduced cognitive- and light-related modulation of pupil size.

Publication guidelines and recommendations for pupillary measurement in psychophysiological studies

A variety of psychological and physical phenomena elicit variations in the diameter of pupil of the eye. Changes in pupil size are mediated by the relative activation of the sphincter pupillae muscle (decrease pupil diameter) and the dilator pupillae muscle (increase pupil diameter), innervated by the parasympathetic and sympathetic branches, respectively, of the autonomic nervous system. The current guidelines are intended to inform and guide psychophysiological research involving pupil measurement by (1) summarizing important aspects concerning the physiology of the pupil, (2) providing methodological and data-analytic guidelines and recommendations, and (3) briefly reviewing psychological phenomena that modulate pupillary reactivity. Because of the increased ease and tractability of pupil measurement, the goal of these guidelines is to promote accurate recording, analysis, and reporting of pupillary data in psychophysiological research.

Sleep deprivation and compensatory cognitive effort on a visual information processing task

STUDY OBJECTIVES

Total sleep deprivation (TSD) is often associated with worse performance on tasks of attention and working memory, but some studies show no performance changes. One possibility is that greater compensatory cognitive effort is put forth to achieve similar results after TSD. We aimed to better understand the relationship between TSD, cognitive engagement, and performance outcomes following TSD.

METHODS

Twenty healthy adults completed cognitive testing following a night of normal sleep and again after ~55 hours of TSD. Participants detected target letters in low (3-item) and high (10-item) load visual letter displays on the span of apprehension task with concurrent pupillometry, a measure of cognitive effort.

RESULTS

We found significantly poorer detection accuracy and marginally longer response times following TSD across both arrays. In both arrays, significantly greater preparatory pupillary responses were found just prior to array onset. There was also a significant session by array interaction for pupillary responses, such that significantly greater dilation was found for the 3-letter array after TSD, while a nonsignificant decline in dilation was found following the 10-letter array after TSD.

CONCLUSIONS

These results suggest a complex relationship between attentional control and cognitive resource allocation following TSD. Sleep-deprived individuals may allocate more compensatory cognitive effort to easier tasks but choose to disengage from more challenging cognitive tasks that have little perceived reward or probability of success to preserve diminishing cognitive resources. More work is needed to better delineate the underlying neurological systems involved in these processing load-dependent attentional control mechanisms after TSD.

Age-related differences in event-related potentials and pupillary responses in cued reaction time tasks

Deficits in the noradrenergic system are associated with age-related cognitive decline, yet how healthy aging influences the functional properties of this arousal system is still poorly understood. We addressed this question in humans using pupillometry, a well-established indicator of activity levels in the locus coeruleus (LC), the main noradrenergic center in the brain. We recorded the pupillogram and the electroencephalogram of 36 young and 39 older adults, while they were engaged in cued reaction time tasks known to elicit LC responses in monkeys. Event-related potentials (ERPs) revealed significant group differences. Older adults showed higher cortical activation during preparatory processes reflected in enhanced cue-evoked frontocentral ERPs and reduced parietal ERPs at the time of the motor response. In contrast, the amplitude of the task-related pupillary responses did not show a significant group effect. Our findings suggest that aging-related changes in cortical processing during motor preparation and execution, as documented by electroencephalogram, are not accompanied by changes in the amplitude of activation of the LC, as documented by pupillography.

Reduced pupil dilation during action preparation in schizophrenia

Impairments in cognitive control-the ability to exert control over thoughts and actions and respond flexibly to the environment-are well-documented in schizophrenia. However, the degree to which experimental task performance reflects true cognitive control impairments or more general alterations in effort, arousal and/or task preparedness is unclear. Pupillary responses can provide insight into these latter factors, as the pupil dilates with degree of cognitive effort and response preparation. In the current study, 16 medicated outpatients with schizophrenia (SZP) and 18 healthy controls performed a task that measures the ability to reactively inhibit and modify a planned action-the double-step task. In this task, participants were required to make a saccade to a visual target. Infrequently, the target jumped to a new location and participants were instructed to rapidly inhibit and change their eye movement plan. Applying a race model of performance, we have previously shown that SZP require more time to inhibit a planned action. In the current analysis, we measured pupil dilation associated with task preparation and found that SZP had a shallower increase in pupil size prior to the onset of the trial. Additionally, reduced magnitude of the pupil response was associated with negative symptom severity in patients. Based on primate neurophysiology and cognitive neuroscience work, we suggest that this blunted pupillary response may reflect abnormalities in a general orienting response or reduced motivational significance of a cue signifying the onset of a preparatory period and that these abnormalities might share an autonomic basis with negative symptoms.

Auditory noise increases the allocation of attention to the mouth, and the eyes pay the price: An eye-tracking study

We investigated the effect of auditory noise added to speech on patterns of looking at faces in 40 toddlers. We hypothesised that noise would increase the difficulty of processing speech, making children allocate more attention to the mouth of the speaker to gain visual speech cues from mouth movements. We also hypothesised that this shift would cause a decrease in fixation time to the eyes, potentially decreasing the ability to monitor gaze. We found that adding noise increased the number of fixations to the mouth area, at the price of a decreased number of fixations to the eyes. Thus, to our knowledge, this is the first study demonstrating a mouth-eyes trade-off between attention allocated to social cues coming from the eyes and linguistic cues coming from the mouth. We also found that children with higher word recognition proficiency and higher average pupil response had an increased likelihood of fixating the mouth, compared to the eyes and the rest of the screen, indicating stronger motivation to decode the speech.

Brain-Derived Neurotrophic Factor Expression in Individuals With Schizophrenia and Healthy Aging: Testing the Accelerated Aging Hypothesis of Schizophrenia

PURPOSE OF REVIEW

Schizophrenia has been hypothesized to be a syndrome of accelerated aging. Brain plasticity is vulnerable to the normal aging process and affected in schizophrenia: brain-derived neurotrophic factor (BDNF) is an important neuroplasticity molecule. The present review explores the accelerated aging hypothesis of schizophrenia by comparing changes in BDNF expression in schizophrenia with aging-associated changes.

RECENT FINDINGS

Individuals with schizophrenia show patterns of increased overall mortality, metabolic abnormalities, and cognitive decline normally observed later in life in the healthy population. An overall decrease is observed in BDNF expression in schizophrenia compared to healthy controls and in older individuals compared to a younger cohort. There is a marked decrease in BDNF levels in the frontal regions and in the periphery among older individuals and those with schizophrenia; however, data for BDNF expression in the occipital, parietal, and temporal cortices and the hippocampus is inconclusive. Accelerated aging hypothesis is supported based on frontal regions and peripheral studies; however, further studies are needed in other brain regions.

A Novel Pupillometric Method for Indexing Word Difficulty in Individuals With and Without Aphasia

PURPOSE

Cognitive effort is a clinically important facet of linguistic processing that is often overlooked in the assessment and treatment of people with aphasia (PWA). Furthermore, there is a paucity of valid ways to index cognitive effort in PWA. The construct of cognitive effort has been indexed for decades via pupillometry (measurement of pupil dilation and constriction during a cognitive task), yet pupillometry has not been implemented in studies including PWA. In the present study, we tested a novel method for indexing cognitive effort during linguistic processing in people with and without aphasia.

METHOD

Forty control participants and 39 PWA listened to semantically easy and difficult single nouns and looked at images while their pupillary responses were monitored. Mean pupil dilation in response to easy versus difficult nouns was calculated to index cognitive effort.

RESULTS

Larger mean pupil dilation values were obtained for difficult compared with easy nouns for both groups.

CONCLUSION

Results provide preliminary evidence that pupillometry can be used to index cognitive effort during linguistic processing of single nouns in people with and without aphasia. Methods for indexing cognitive effort will be a valuable addition to existing assessment methods. Suggestions for further research are offered.

Neurocognition, functional competence and self-reported functional impairment in psychometrically defined schizotypy

INTRODUCTION

Schizotypy is phenologically and genetically related to schizophrenia-spectrum illness. Previous studies find cognitive function to be mildly impaired, but specific impairments and their relationship to functioning are not well understood. In this study, we sought to examine how cognitive load affects performance in schizotypy and to examine whether impairments might manifest in functional capacity and quality of life.

METHODS

Undergraduate students were screened for abnormally high levels of schizotypy (N = 72) and compared to those without psychopathology (N = 80) on a standard battery of neuropsychological tests, cognitive tests with varying cognitive load, functional capacity measures and quality of life.

RESULTS

The high schizotypy group did not differ from controls on traditional measures of neuropsychological functioning, but an interaction of group by cognitive load was observed, where those with schizotypy manifested a greater decline in performance as information processing load was parametrically increased. Differences in functioning were observed and cognitive impairment was associated with impaired functioning.

CONCLUSIONS

Cognitive and functional impairment can be observed in those with high schizotypal traits who are non-treatment seeking. The sensitivity of cognitive tests to impairment in this population might be a function of their ability to parametrically increase cognitive load.

Age or age at onset? Which of them really matters for neuro and social cognition in schizophrenia?

In schizophrenia patients, both an older age and earlier age at onset of the disease are related to worse cognitive functioning. As patients with later schizophrenia onset are also older, analysing the two effects separately can be misleading, as they can either be spurious or cancel one another out. The purpose of the present study was to elucidate the effects of age and onset-age on cognition in schizophrenia patients. Individuals with schizophrenia (N=151), aged 18-59 years, were examined with a MATRICS Consensus Cognitive Battery (MCCB) to get a full picture of their cognitive performance. Results showed age and age at onset indeed interrelated. Regression analyses revealed later onset of schizophrenia related to better social cognition. Patients׳ older age was related to a slower performance in symbol coding task, less effective executive functions, worse visual learning, lower attention, and lower total score in the MCCB. In the above regression analyses we controlled doses of antipsychotic medications. The results suggest that a previously found relationship between older age and social cognition might be spurious, and strengthen observations that it is specifically later onset-age which fosters better social cognition in schizophrenia patients.

Cognitive aspects of schizophrenia

Cognitive impairments are a central feature of schizophrenia and are present in most, if not all, cases. There are multiple domains of impairment seen and the level of severity of impairment is considerable. Impairments can be detected prior to the onset of clinical symptoms and the course of impairments involves some subtle early worsening followed by stability in most cases. Cognitive impairments are associated with functional disability, particularly in domains of vocational functioning and independence of residence. Both pharmacological and cognitive remediation interventions have been employed for the treatment of these impairments, with greater progress to date being made in cognitive remediation interventions. While much is known about cognitive impairments, treatment efforts are still in an early stage of development. WIREs Cogn Sci 2013, 4:599-608. doi: 10.1002/wcs.1253 CONFLICT OF INTEREST: Dr. Harvey has received consulting fees from Abbott Labs, Amgen, Boehringer Ingelheim, Genentech, Johnson and Johnson, Pharma Neuroboost, Roche Parma, Sunovion Pharma, and Takeda Pharma during the past year. For further resources related to this article, please visit the WIREs website.

Computerized neurocognitive test performance in schizophrenia: a lifespan analysis

OBJECTIVE

Computerized neurocognitive batteries based on advanced behavioral neuroscience methods are increasingly used in large-scale clinical and genomic studies. Favorable construct validity in younger schizophrenia patients has been reported, but not in older patients. New variables afforded by computerized assessments were used to clarify age-associated cognitive impairment across the lifespan.

METHODS

624 patients with schizophrenia and 624 healthy comparison (HC) subjects age 16-75 completed a 1-2-hour computerized neurocognitive battery (CNB) that assessed abstraction and mental flexibility, attention, working memory, recognition memory (verbal, facial, spatial), language, visuospatial, and emotion processing. Linear mixed effects models tested for group differences in accuracy, response time, and efficiency scores. Contrasts were stratified by age.

RESULTS

91% of older (45+) and 94% of younger (< 45) groups provided "good" data quality. After controlling for parental education and project, there were significant three-way interactions for diagnosis x domain x age group on all three outcome variables. Patients performed worse than HC across all neurocognitive domains, except in the oldest group of 60+ patients. Age-stratified analyses did not show differences between younger (16-45) and older patients (45-60, 60+), except for the attention domain. Older patients' reduced working memory efficiency was due to worse speed, not accuracy. Older patients were quicker than younger patients in processing emotions.

CONCLUSIONS

Computerized assessments are feasible in large cohorts of schizophrenia patients. There is stable and generalized neurocognitive dysfunction across the lifespan in schizophrenia, albeit with fewer differences in some domains between older patients and HC after age 60. Speed-accuracy tradeoff strategies suggest deceleration of some frontal networks and improvements in speed of emotional processing.

Neuropsychological performance in older patients with schizophrenia: a meta-analysis of cross-sectional and longitudinal studies

OBJECTIVE

Cognitive deficits are among the most reliable predictors of functional impairment in schizophrenia and a particular concern for older individuals with schizophrenia. Previous reviews have focused on the nature and course of cognitive impairments in younger cohorts, but a quantitative meta-analysis in older patients is pending.

METHOD

A previously used search strategy identified studies assessing performance on tests of global cognition and specific neuropsychological domains in older patients with schizophrenia and age-matched comparison groups. Both cross-sectional and longitudinal studies were included. Potential methodological, demographic, and clinical moderators were analyzed.

RESULTS

Twenty-nine cross-sectional (2110 patients, 1738 comparison subjects) and 14 longitudinal (954 patients) studies met inclusion criteria. Patients were approximately 65 years old, with 11 years of education, 53% male and 79% Caucasian. Longitudinal analysis (range 1-6 years) revealed homogeneity with small effect sizes (d = -0.097) being observed. Cross-sectional analyses revealed large and heterogeneous deficits in global cognition (d = -1.19) and on specific neuropsychological tests (d = -0.7 to -1.14). Moderator analysis revealed a significant role for demographic (age, sex, education, race) and clinical factors (diagnosis, inpatient status, age of onset, duration of illness, positive and negative symptomology). Medication status (medicated vs nonmedicated) and chlorpromazine equivalents were inconsequential, albeit underrepresented.

CONCLUSIONS

Large and generalized cognitive deficits in older individuals with schizophrenia represent a robust finding paralleling impairments across the life span, but these deficits do not decline over a 1-6 year period. The importance of considering demographic and clinical moderators in cross-sectional analyses is highlighted.

Classification of schizophrenia using feature-based morphometry

The objective of this study was to use a combined local descriptor, namely scale invariance feature transform (SIFT), and a non linear support vector machine (SVM) technique to automatically classify patients with schizophrenia. The dorsolateral prefrontal cortex (DLPFC), considered a reliable neuroanatomical marker of the disease, was chosen as region of interest (ROI). Fifty-four schizophrenia patients and 54 age- and gender-matched normal controls were studied with a 1.5T MRI (slice thickness 1.25 mm). Three steps were conducted: (1) landmark detection and description of the DLPFC, (2) feature vocabulary construction and Bag-of-Words (BoW) computation for brain representation, (3) SVM classification which adopted the local kernel to implicitly implement the feature matching. Moreover, a new weighting approach was proposed to take into account the discriminant relevance of the detected groups of features. Substantial results were obtained for the classification of the whole dataset (left side 75%, right side 66.38%). The performances were higher when females (left side 84.09%, right side 77.27%) and seniors (left side 81.25%, right side 70.83%) were considered separately. In general, the supervised weighed functions increased the efficacy in all the analyses. No effects of age, gender, antipsychotic treatment and chronicity were shown on DLPFC volumes. This integrated innovative ROI-SVM approach allows to reliably detect subjects with schizophrenia, based on a structural brain marker for the disease such as the DLPFC. Such classification should be performed in first-episode patients in future studies, by considering males and females separately.

Oculomotor and pupillometric indices of pro- and antisaccade performance in youth-onset psychosis and attention deficit/hyperactivity disorder

The goals of the study were to examine inhibitory deficits on the antisaccade task in 8- to 20-year olds with youth-onset psychosis or attention deficit/hyperactivity disorder (ADHD) and healthy controls and to examine if age-related changes in performance differed across groups. In addition to the conventional measures of performance, pupillary dilations were used to obtain estimates of phasic and tonic level of arousal. Results showed that the psychosis, but not the ADHD, group had elevated antisaccade error rates; however, variability of error rates was high in all groups. These inhibitory failures were accompanied by a lower level of momentary cognitive effort (as indexed by pupillary dilations). The largest differences between the control and clinical groups were found not in the expected indices of inhibition but in the probability of correcting inhibitory errors and in variability of antisaccade response times, which were correlated with each other. These findings did not appear to be attributable to a deficit in maintaining task instructions in mind in either disorder or lack of motivation in ADHD. Instead, results point to impairments in both clinical groups in sustaining attention on a trial-by-trial basis, resulting in deficits in self-monitoring. Thus, results show inhibitory deficits in the context of more general attentional impairments in both disorders.

The course of neuropsychological performance and functional capacity in older patients with schizophrenia: influences of previous history of long-term institutional stay

BACKGROUND

Chronically institutionalized patients with schizophrenia have been reported to manifest cognitive and functional decline. Previous studies were limited by the fact that current environment could not be separated from lifetime illness course. The present study examined older outpatients who varied in their lifetime history of long-term psychiatric inpatient stay.

METHODS

Community-dwelling patients with schizophrenia (n = 111) and healthy comparison subjects (n = 76) were followed up to 45 months and examined two or more times with a neuropsychological battery and performance-based measures of everyday living skills (University of California San Diego Performance-Based Skills Assessment Battery [UPSA]) and social competence. A mixed-effects model repeated-measures method was used to examine changes.

RESULTS

There was a significant effect of institutional stay on the course of the UPSA. When the schizophrenia patients who completed all three assessments were divided on the basis of length of institutional stay and compared with healthy comparison subjects, patients with longer stays worsened on the UPSA and social competence, while patients with shorter stays improved. For neuropsychological performance, both patient samples worsened slightly, while the healthy comparison group manifested a practice effect. Reliable change index analyses showed that worsening on the UPSA for longer stay patients was definitely nonrandom.

CONCLUSIONS

Lifetime history of institutional stay was associated with worsening on measures of social and everyday living skills. Neuropsychological performance in schizophrenia did not evidence the practice effect seen in the healthy comparison sample. These data suggest that schizophrenia patients with a history of long institutional stay may worsen even if they are no longer institutionalized.

Cognitive deficits in recent-onset and chronic schizophrenia

Although cognitive dysfunction is a primary characteristic of schizophrenia, only recently have investigations begun to pinpoint when the dysfunction develops in the individual afflicted by the disorder. Research to date provides evidence for significant cognitive impairments prior to disorder onset. Less is known about the course of cognitive dysfunction from onset to the chronic phase of schizophrenia. Although longitudinal studies are optimal for assessing stability of cognitive deficits, practice effects often confound assessments, and large and representative subject samples have not been followed over long periods of time. We report results of a cross-sectional study of cognitive deficits early and late in the course of schizophrenia carried out at four different geographic locations to increase sample size and generalizability of findings. We examined a broad set of cognitive functions in 41 recent-onset schizophrenia patients and 106 chronic schizophrenia patients. The study included separate groups of 43 matched controls for the recent-onset sample and 105 matched controls for the chronic schizophrenia sample in order to evaluate the effects of cohort (i.e., age) and diagnosis (i.e., schizophrenia) on cognitive functions. All measures of cognitive function showed effects of diagnosis; however, select time-based measures of problem solving and fine motor dexterity exhibited interactions of diagnosis and cohort indicating that these deficits may progress beyond what is expected with normal aging. Also, worse recall of material in episodic memory was associated with greater length of illness. Nevertheless, findings indicate that nearly all cognitive deficits are comparably impaired across recent-onset and chronic schizophrenia.

Pupillometric measures of attentional allocation to target and mask processing on the backward masking task in schizophrenia

Allocation of attentional resources during early visual processing was investigated in schizophrenia. Pupillary responses were recorded during a backward masking task as an index of resource allocation in schizophrenia patients (n=51) and nonpsychiatric controls (n=51). Two time-linked components of pupillary response waveforms appeared to differentially index resource allocation to targets versus masks. Two patient subgroups were identified: One with normal overall pupillary responses (resource allocation), but greater allocation on mask relative to target components, and another with abnormally small overall pupillary responses and similar allocation between target and mask components. Thus, misallocation of resources to masks contributed to masking deficits in one subgroup, whereas reduced resource allocation contributed to deficits in the other. The nature of resource-related deficits can vary across schizophrenia subgroups.

Is schizophrenia a syndrome of accelerated aging?

Schizophrenia is associated with a number of anatomical and physiological abnormalities outside of the brain, as well as with a decrease in average life span estimated at 20% in the United States. Some studies suggest that this increased mortality is not entirely due to associated causes such as suicide and the use of psychotropic medications. In this article, in order to focus greater attention on the increased mortality associated with schizophrenia, we present a special case of the hypothesis that physiological abnormalities associated with schizophrenia make a contribution to the increased mortality of schizophrenia: specifically, the hypothesis that schizophrenia is a syndrome of accelerated aging. Evidence consistent with this hypothesis comes from several areas. The biological plausibility of the hypothesis is supported by the existence of established syndromes of accelerated aging and by the sharing of risk factors between schizophrenia and other age-related conditions. We propose methods for testing the hypothesis.

Age-associated differences in cognitive performance in older community dwelling schizophrenia patients: differential sensitivity of clinical neuropsychological and experimental information processing tests

Cognitive dysfunction is a common feature of schizophrenia and deficits are present before the onset of psychosis, and are moderate to severe by the time of the first episode. Controversy exists over the course of cognitive dysfunction after the first episode. This study examined age-associated differences in performance on clinical neuropsychological (NP) and information processing tasks in a sample of geriatric community living schizophrenia patients (n=172). Compared to healthy control subjects (n=70), people with schizophrenia did not differ on NP tests across age groups but showed evidence for age-associated cognitive worsening on the more complex components of an information-processing test. Age-related changes in cognitive function in schizophrenia may be a function of both the course of illness and the processing demands of the cognitive measure of interest. Tests with fixed difficulty, such as clinical NP tests, may differ in their sensitivity from tests for which parametric difficulty manipulations can be performed.

Attentional capture in schizophrenia and schizotypy: effect of attentional load

INTRODUCTION

We examined the effect of attentional load on attentional capture in schizophrenia. On the basis of the ''resource limitations hypothesis'' in schizophrenia, we propose that attentional capture by an irrelevant distractor will be differentially affected by the attentional load for patients and healthy controls.

METHOD

70 patients with schizophrenia, 15 schizotypals, and 54 controls were asked to attend to a central task while a lateral distractor moved. Participants were instructed either (i) to localise a black square (low-load condition), or (ii) to locate the larger number between two 1-digit numbers (medium-load condition), or (iii) to locate the larger number between two several-digit numbers (high-load condition). In the baseline condition, no distractor moved.

RESULTS

All groups showed attentional capture in the low-load condition. Patients and schizotypals resisted interference from the distractor in the medium and highload conditions. Controls resisted interference in the high-load condition.

CONCLUSION

The results suggest that attentional modulation is impaired in schizophrenia and in the schizophrenia spectrum.

Finding of abnormal scanning behavior in the Span of Apprehension task in schizophrenia but diagnostic non-specificity of sum scores

Deficits in the Span of Apprehension (SOA) task have been discussed controversially as a trait marker of schizophrenia. The task was administered to 47 schizophrenia and 48 depressed patients as well as to 46 controls. Results indicate a non-specificity of the SOA sum scores but differential abnormalities in spatial visual processing.

Effortful cognitive resource allocation and negative symptom severity in chronic schizophrenia

BACKGROUND

The relationship between negative symptoms, early visual information-processing deficits, and effortful processing resource allocation was investigated.

METHODS

Older patients with chronic schizophrenia (n = 58) and healthy controls (n = 71) participated. Pupillary responses were recorded during performance of the span of apprehension task (blocks of 3- and 10-letter arrays) as an index of resource allocation or mental effort during the task.

RESULTS

Patients and controls showed larger pupillary responses in higher relative to lower processing loads both during array processing and just prior to array onset (preparation). Both groups, therefore, invested more cognitive effort preparing for and then processing larger arrays. A subgroup of patients with abnormally small pupillary responses and impaired performance showed greater negative symptom severity relative to a subgroup of patients with normal pupillary responses. Smaller pupillary responses in the patients were also significantly correlated with greater negative symptom severity, independent of positive symptom severity. Patients with reduced effortful resource allocation, therefore, exhibited greater negative symptomatology. A subgroup of patients with normal pupillary responses still showed impaired detection accuracy relative to controls, suggesting that reduced cognitive effort or resource allocation problems cannot account for impairments in early visual information processing in this subgroup.

CONCLUSIONS

The study illustrates important relationships between cognitive effort and performance that can impact conclusions about the nature of cognitive impairments and associations between negative symptoms and neurocognition in schizophrenia.

Regulation of cognitive resources during sustained attention and working memory in 10-year-olds and adults

We examined differences between 10-year-olds and young adults in resource recruitment and regulation during tasks of sustained attention and spatial working memory. We administered participants spatial 0- and 1-back tasks and used pupillary dilation as a measure of resource recruitment. Repeated administration of 0-back led to smaller pupillary dilations and greater response time (RT) variability, revealing a vigilance decrement. Effects of repeated administration of 0-back and differences between 0- and 1-back in d' and RTs were similar between ages. Results further suggested that the children may not have been as effective as adults in extracting frequency information. Thus, on simple tasks of sustained attention and working memory, children recruit resources in a manner similar to adults. Finally, d' was correlated with RT variability on both tasks at both ages, highlighting the role of attentional fluctuations on both tasks.

Comparison of three computer-administered cognitive tasks as putative endophenotypes of schizophrenia

It has been repeatedly demonstrated that individuals with schizotypal personality features (SPF) exhibit similar endophenotypic traits as persons with schizophrenia. Less research has compared the relative sensitivity of different endophenotypes in the same sample of individuals with SPF. Fourteen university students with SPF (mean age 20.5+/-1.6; 43% male) and 26 controls (mean age 20.3+/-1.1; 31% male) were defined by the Abbreviated Schizotypal Personality Questionnaire (SPQ-B). All participants reported no known biological relative with schizophrenia. Participants completed three computer-administered cognitive tasks: a 6-min degraded-stimuli A-X Continuous Performance Test (CPT), the Wisconsin Card Sort Test (WCST), and a Span of Apprehension (SOA) task (6- and 12-letter arrays). On the CPT, only omission errors resulted in a statistically significant group difference, U=115.5, p=.05, Cohen's d=0.54 (medium effect size), with the SPF group (mean errors: 3.43+/-3.28) making more omission errors than controls (mean errors: 1.88+/-2.66). Notably, 46% of the controls had no omission errors, compared to 14% of the SPF group. The only SPQ-B factor score to show a statistically significant linear relationship with CPT omission errors was the Cognitive-Perceptual factor (rs=.33, p=.04). Group differences on performance indices from the SOA and WCST did not approach statistical significance. Based on performance from the community-identified schizotypes, results suggest that performance on the CPT may represent a more robust endophenotype of schizophrenia, compared to the SOA and WCST.

Olfactory functioning in schizophrenia: relationship to clinical, neuropsychological, and volumetric MRI measures

Deficits in odor identification and detection threshold sensitivity have been observed in schizophrenia but their relationship to clinical, cognitive, and biologic measures have not been clearly established. Our objectives were to examine the relationship between measures of odor identification and detection threshold sensitivity and clinical, neuropsychological, and anatomic brain measures. Twenty-one patients with schizophrenia and 20 healthy controls were administered psychophysical tests of odor identification and detection threshold sensitivity to phenyl ethyl alcohol. In addition, clinical symptom ratings, neuropsychological measures of frontal and temporal lobe function and whole brain MRIs were concurrently obtained. Patients exhibited significant deficits in odor identification but normal detection threshold sensitivity. Poorer odor identification scores were associated with longer duration of illness, increased negative and disorganized symptoms, and the deficit syndrome, as well as impairments in verbal and nonverbal memory. Better odor detection thresholds were specifically associated with first-rank or productive symptoms. Larger left temporal lobe volumes with MRI were associated with better odor identification in controls but not in patients. Given the relevance of the neural substrate, and the evidence of performance deficits, psychophysical probes of the integrity of the olfactory system hold special promise for illuminating aspects of the neurobiology underlying schizophrenia.

Dual-task information processing in schizotypal personality disorder: Evidence of impaired processing capacity

Working memory theories heavily rely on the concept of processing resources and the their efficient deployment. Some recent work with schizophrenia-spectrum patients has suggested that many associated cognitive impairments may be reduced to deficits in working memory, possibly related to reductions in information-processing capacity resources. In this study, 38 patients with schizotypal personality disorder (SPD), 22 patients with other personality disorders, and 14 healthy comparison participants performed a dual-task processing assessment that was designed specifically for use in this type of study. Participants recalled lists of digits at their predetermined maximum digit span and performed box-checking tests, first alone and then in a dual-task format. Instructions included equal prioritization of both tasks. SPD patients had significantly shorter digit spans, and they also showed more deterioration on both tasks. Performance operating characteristics curves indicated that SPD patients' reduced performance was not due to abnormal resource allocation strategies leading to strategic failures. The authors discuss the implications of these processing capacity limitations for understanding both the signature of cognitive impairment within the schizophrenia spectrum and general abnormalities in working memory.

Cognition in schizophrenia: impairments, determinants, and functional importance

Recent findings support and add to earlier findings of cognitive dysfunction in schizophrenia. Deficits across neurocognitive domains such as attention, working memory, language skills, and executive functioning tend to be moderate, with the most pronounced deficits found in verbal learning and memory. All these neurocognitive domains are related to adaptive and social skills, with executive functions and verbal learning and memory showing more variance across more domains than other neuro-cognitive variables. Negative symptoms and neurocognitive domains, although correlated, are distinct and have differential pathways of change with treatment. General psychopathology symptoms, such as depression and anxiety, may become important treatment targets as strategies are developed for translating cognitive enhancement to real-world functional performance.

Lateralization of pupillary light reflex parameters

OBJECTIVE

The aim of this study was to determine differing reactions of the left and right eyes with regard to pupillary light reflex (PLR) parameters.

METHODS

All together 90 healthy subjects were included. In the first test series, 34 subjects were investigated on both eyes (left eye was tested first, three tests per day and one reliability test). In the second test series, 32 subjects were studied while changing the beginning side. In the last test series, 29 subjects were investigated 12 times each within 1h (beginning side changed, without spoken advice). Infrared pupillometry was used to study pupil diameter, latency time, relative amplitude, contraction/dilation velocity, and pupil redilation time.

RESULTS

The study demonstrated significant differences of PLR parameters between both eyes. In contrast to the pupil diameter of the left eye the parasympathetically-dominated right eye was not influenced by vocal instructions or by changing the beginning side.

CONCLUSIONS

PLR parameters might indicate functional lateralization of autonomic function in the central nervous system. High sensitivity of the procedure (arousal due to spoken advice, time of day) is advantageous for various psychophysiological investigations.

SIGNIFICANCE

Differences between both eyes might point towards cortical lateralization of central autonomic function.

Measuring cognitive insight in middle-aged and older patients with psychotic disorders

The study examined the psychometric properties, factor structure and validity of a recently developed measure of insight, the Beck Cognitive Insight Scale (BCIS) and tested the relationship between the BCIS and psychiatric symptoms in a sample of middle-aged and older patients with schizophrenia or schizoaffective disorder. The BCIS measures the ability of respondents to observe and question their cognitive processes, whereas other insight scales focus primarily on knowledge about the presence of an illness and need for treatment. Participants were 164 middle-aged and older outpatients with schizophrenia or schizoaffective disorder who completed a battery of measures assessing insight, symptoms of schizophrenia and symptoms of depression. The results of a confirmatory factor analysis (CFA) supported the two-factor structure previously reported for the BCIS, with one factor labeled self-reflectiveness and the other labeled self-certainty. The BCIS showed adequate reliability and a moderate correlation with the Birchwood Insight Scale (IS). The BCIS correlated with some PANSS subscales measuring symptoms of schizophrenia, but did not correlate at a significant level with symptoms of depression. The findings suggest that middle-aged and older outpatients with schizophrenia or schizoaffective disorder respond on the BCIS in a manner similar to a younger inpatient population. This instrument is a promising tool for measuring the role of cognitive change in a broad range of patients experiencing psychosis.

Psychosocial functioning on the Independent Living Skills Survey in older outpatients with schizophrenia

Improving real-life community functioning in patients with severe mental illness has been an important recent focus of treatment outcome research. Few studies, however, have examined psychosocial functioning in older psychotic patients. The Independent Living Skills Survey (ILSS) is a measure of the basic functional living skills of individuals with severe and persistent mental illness. The self-report version of the ILSS was administered to 57 middle-aged and older community dwelling outpatients with schizophrenia and 40 age-comparable nonpsychiatric participants. Regardless of whether patients resided in assisted living or independent settings, they showed significantly impaired functioning on a majority of the functional areas assessed by the ILSS. No consistent relationship was found between symptom severity and functioning. With certain modifications, the ILSS appears to be a sensitive indicator of functional impairment in this older sample of community-dwelling outpatients with schizophrenia. Information provided by the instrument might be useful to guide rehabilitation efforts and measure functioning changes in response to treatment in this population.

Pupillary dilation to simple vs. complex tasks and its relationship to thought disturbance in schizophrenia patients

Task-evoked pupil dilation is a measure of attentional allocation. Schizophrenia patients have pupil dilation deficits during high cognitive load tasks, which have been attributed to attentional resource deficits. Moreover, this attentional impairment is thought to be linked to cognitive fragmentation and thought disturbance. Previous attempts to associate attentional deficits to thought disturbance have typically measured these domains at distinct times, incorrectly assuming that both are static variables. In this study, we compared the pupil dilation of 24 schizophrenia patients to 15 non-patients during complex (Rorschach blots) vs. simple visual (line drawings) processing tasks while simultaneously assessing their verbal responses for thought disturbance. Schizophrenia patients' dilation to the simple stimuli was similar to the non-patients; however, they demonstrated significantly less dilation to the complex stimuli. Reduced dilation was also significantly correlated with reduced response complexity and more severe thought disorder. The results suggest that, in the face of complex problem-solving situations, greater attentional impairment and cognitive overload in schizophrenia is associated with higher levels of disturbed and impoverished thinking. These findings support the 'resource limitations hypothesis' of schizophrenia and underscore the utility of a simultaneous paradigm when studying the relationship between attentional deficits and thought disturbance.

Accelerated age-related decline of visual information processing in first-degree relatives of persons with schizophrenia

A recent cross-sectional study suggested that persons with schizophrenia experience an accelerated age-related decline in performance on the Span of Apprehension task, a visual information processing paradigm. However, this study was not able to determine if such decline was primarily related to genetic loading for schizophrenia, as the decline may have been related to chronic neuroleptic use or other confounds found when studying persons with schizophrenia directly. To help address this question, the current study examined healthy first-degree relatives of persons with schizophrenia over a wide age range to investigate whether such age effects may be related to genetic loading for schizophrenia. Twenty-eight healthy first-degree relatives of persons with schizophrenia (ages 21-72) and 31 healthy controls (ages 19-75) were evaluated using the Span of Apprehension task with cross-sectional methodology. Results replicated and extended the earlier report examining persons with schizophrenia, as the data indicated a statistically significant accelerated age-related decline in performance in the relatives. While the study is limited by cross-sectional methodology, it suggests a genetically driven, age-related decline in visual information processing related to schizophrenia and informs future longitudinal studies that can more definitively address such a possibility.

Pupillary responses and attentional allocation problems on the backward masking task in schizophrenia

Early visual information processing impairment has consistently been found on the backward masking task in patients with schizophrenia, but the nature of this impairment remains unclear. Pupillometry was used to measure attentional allocation during visual backward masking task performance in patients with schizophrenia (n=16) and nonpsychiatric controls (n=16). The extent of pupil dilation recorded during a cognitive task reflects the processing load placed on the nervous system by the task. Schizophrenia patients detected significantly fewer targets than controls only when the stimulus onset asynchrony (SOA) between targets and masks reached 317 ms. For both groups, peak pupil dilation responses were also significantly larger in the 317 ms SOA condition relative to a no-mask condition, suggesting that the processing load of the 317 SOA masking condition was greater than the no-mask condition. In addition, a principal components analysis of pupillary response waveforms identified time-related factors that appeared to differentially index attentional allocation to targets vs. masks. Patients with schizophrenia showed less dilation than controls on a middle factor that appeared to index attentional allocation to targets, but patients showed greater dilation than controls on a late factor that appeared to index attentional allocation to masks. That is, controls attended more to targets than to masks, but patients attended more to masks than to targets. These findings suggest that masking impairments at SOA intervals greater than 100-200 ms may be due abnormalities in attentional allocation mechanisms.

Aging and outcome in schizophrenia

OBJECTIVE

Controversy exists about long-term outcome of schizophrenia, but few studies have compared older out-patients to normal subjects. We sought to examine the relationship of age to clinical features, psychopathology, movement abnormalities, quality of well-being, and everyday functioning in schizophrenia out-patients and normal comparison subjects, and to further characterize these outcomes in elderly schizophrenia out-patients.

METHOD

A total of 290 out-patients and 144 comparison subjects, aged 40-85 years, underwent comprehensive assessments.

RESULTS

Among patients, aging was associated with decreased psychopathology, even after controlling for duration of illness. There was no accelerated aging-related decline on any measure in the patients. Yet, elderly patients were more impaired than comparison subjects on various measures.

CONCLUSION

The course of schizophrenia in late life appears stable, but most elderly patients remain symptomatic and impaired. Our findings dispute notions of either progressive deterioration or marked improvement in aging schizophrenia out-patients.

Cognition in schizophrenia

Cognitive dysfunction has been described as a hallmark feature of schizophrenia since the first descriptions of the illness. Kraepelin described a number of features of the disorder that he thought reflected impairments in cognition and attention. He also speculated that cognitive impairments were mediated by neurobiologic dysfunction, specifically impairments in the functions of the frontal lobe. Since Kraepelin's time, there have been many changes in the general conceptions of schizophrenia, including ideas regarding the status and importance of cognitive impairment in the illness. Due to increased sophistication of neuropsychologic assessment and neuroimaging techniques, cognitive impairment has again has risen to the forefront of importance in terms of theories regarding the etiology and treatment of schizophrenia.